I'm not sure how much research you've already done, so if you already know this please forgive.

Collections agencies / services are HIGHLY regulated both by federal and state laws. If you haven't already you will want to look up:

The Fair debt Collection Practices Act
Fair Credit Reporting Act
Collection Agency Regulations for your state

These are just the ones I know about as a consumer. I'm sure this is doable, but you don't want to open yourself to any liability for not following the applicable laws.

rachel@knoxvillebookkeeper.com